1. Field of the Invention
This invention generally relates to a planetary gear transmission. More specifically, this invention pertains to a planetary gear transmission having a carrier comprised of divided carrier parts between which a sun gear and planetary gears are disposed.
2. Related Art Description
A planetary gear transmission having a divided-type carrier is disclosed in Japanese Patent Application No. HEI 2-2334 filed on Jan. 9, 1990 in the name of the same assignee of the present patent application. This planetary gear transmission has a sun gear, a plurality of planetary gears meshed with the sun gear, a carrier for supporting the planetary gears rotationally, and an internal gear meshed with the planetary gears. The carrier is constituted by first and second carrier parts positioned opposite in the axial direction, between which the sun and planetary gears are accommodated. The first and second carrier parts are fixed by a plurality of fastening bolts. The internal gear is formed circumferentially on the inner surface of a ring member. The ring member has inner surface portions on both sides of the internal gear portion. These inner surface portions support rotationally the first and second carrier parts via ball bearings, respectively.
In the planetary gear transmission of this type, the sun and planetary gears are accommodated inside the carrier parts and the internal gear, so that the axial length of the transmission can be reduced compared to other types of planetary gear transmissions. Further, it is dynamically advantageous that the carrier having first and second carrier parts is supported on both sides by the ring member via the ball bearings.
This invention is directed to improvements of a planetary gear transmission having a divided-type carrier.
One object of this invention is to provide a planetary gear transmission with a mechanism for equally distributing load among gear elements even if manufacturing errors or misalignment of the parts occur.
Another object of this invention is to lower the noise generated from a planetary gear transmission having a divided-type carrier.
Still another object of this invention is to produce a planetary gear transmission having a divided-type carrier compactly.